Biology Chapter 5

Phospholipid bi-layer with cholesterol and proteins

Ce

Cell Membrane 

Hydrophobic tailHydrophilic head

*controls what goes in/out*maintains homeostasis

Membrane Proteins

Transportation

Enzymatic Activity

Signal Transduction 

Cell-Cell Recognition

Intercellular Joining 

Attach to Cytoskeleton & ECM

Protein pumps> active transport 

Ex) aquaporins: water goes through (selective permeability) 

May be an enzyme with an active site 

Hook together in cell junctions, long-lasting binding

Identification tags 

Signal goes off if something is wrong 

glycoproteins/glycolipids

Keeps things in tact 

Signal to receptor Chemical messenger (hormone)

TYPES OF PROTEINS 

Integral Proteins

Inside of membrane; made of nonpolar amino acids in alpha helixes 

Channel Proteins

Peripheral Proteins

loosely bounded to surface exposed to integral proteins

SYNTHESIS OF MEMBRANES

-Membrane proteins and lipids made in ER -In golgi, glycolipids/proteins get carbohydrate modification -glycolipids/proteins transported to plasma membrane -exocytosis; puts glyc./prot. outside of membrane

PASSIVE TRANSPORT

ACTIVE TRANSPORT

diffusion- molecules moves through membrane (through available space) 

MORE -------> LESS concentrated

OSMOSIS

Diffusion of water across a selectively permeable membrane

Tonicity- a solution's ability to lose/gain water 

water potential= solute potential + pressure potential 

Facilitated Diffusion

Moving a substance against (up) concentration gradient 

Entropy

Endocytosis- bulk movement of stuff into the cell

Na+ and K+ pump

Wa

Water Potential 

Hypertonic:-high water potential outside of cell-high concentration outside of cell

Isotonic:- = concentration in/out-water still moves in/out of cell

CELL SIGNALING

1) paracrine signaling (local) synaptic signaling (local) 2) endocrine signaling (long distance)

Reception

Transduction

Response

How

How do we terminate the response?

Membrane Transport

Cell Signaling

Membrane Proteins

Passive/ Active Transport